1. Field of the Invention
The present disclosure relates to liquid crystal display technology, and more particularly to a liquid crystal device (LCD) and the driving method thereof.
2. Discussion of the Related Art
LCDs are characterized by attributes such as thinner, power-saving, low radiation, and the emitted soft lights are not harm to human eyes, and thus are widely adopted. The LCD mainly includes a liquid crystal panel and a backlight module opposite to the liquid crystal panel. In addition, the backlight module provides a light source for the liquid crystal panel such that the liquid crystal panel can display images via the light beams emitted from the light source.
Currently, most of liquid crystal displays (LCDs) or organic light emitting diode (OLED) displays include at least one pixel cell having a red (R) subpixel, a green (G) subpixel and a blue (B) subpixel. The grayscale values of each of the subpixels are controlled so as to mix the displayed color of one colorful image. With the development of the information technology, a great variety of demands toward display panels come out recently, such as high transmission rate, low power consumption, and high display performance. As the transmission rate and the mixing efficiency of the above RGB color-mixing method is relatively low, the power consumption of the display panel is high, which slows down the panel enhancement. In view of the above, a new pixel cell having the R subpixel, a G subpixel, a B subpixel, and a fourth subpixel has been developed so as to enhance the display performance of the RGB display panel.
Normally, the fourth subpixel is the white (W) subpixel. The advantage of the RGBW four-pixel-display includes: (1) the resolution of the subpixel is increased by the ratio of 1/4; (2) the transmission rate of the subpixel is increased by at least 50 percent; (3) the number of colors of RGBW is greater than that of the RGB for 11/16.
U.S. Pat. No. 7,277,075 B1 discloses a liquid crystal device having RGBW subpixels. The liquid crystal device obtains the RGB information from an inputted image signals. The RGB information includes output values respectively for white (Wo), for red (Ro), for green (Go) and for blue (Bo). The output values of the liquid crystal device satisfy the equation below:Ri:Gi:Bi=(Ro+Wo):(Go+Wo):(Bo+Wo);
Wherein Ri, Gi, and Bi respectively represents the input value for red, green, and blue within the converted RGB information.
However, when the liquid crystal device displays the white color, the proportions of the first chromaticity value (x) and the second chromaticity value (y) forming the white color is a fixed value when the grayscale values is greater than a threshold grayscale value, such as the grayscale value in FIG. 1 as indicated by “M.” When the grayscale value is not greater than the threshold grayscale value, the proportions of the first chromaticity value (x) and the second chromaticity value (y) of the white color are different. For this reason, the outputted values for each color calculated by the above equations may be not precise enough when the grayscale value is not greater than the threshold grayscale value.